This invention relates to a vessel for oceanic fishing and a method of fish handling from entrapment through on-board processing.
This invention finds particular utilization in the area of off-shore fishing of tuna and similarly large fish which are found in quantity in large schools. Such schools of fish are presently captured utilizing five well known techniques. They are, longline, pole and line, purse-seine, trailing and traps. Longline fishing generally utilizes a series of hooks, on the order of 2,000 attached by leader wires to a very long main line which may be in the range of approximately 50 miles. At the beginning of each fishing day, the hooks are manually baited utilizing fish (saury), and the main line together with its leaders and hooks, attached at uniformly spaced intervals is let out while the vessel steams through the potential fishing waters. The main line is selectively ballasted so that it is placed at the subsurface location of the feeding grounds of large, deep swimming tuna (generally approximately 50 fathoms). With this type of system, only one set and retrieval of the gear is made by the fishing vessel during each working day. As is appreciated, this technique is arduous and relies heavily on manual labor.
The second technique, pole and line, have been employed extensively when used in conjunction with small fishing vessels. Essentially, vessels of this type carry live bait which is thrown to a attract surface schools of tuna which are subsequently hooked and brought on board.
Purse seining utilizes a long, deep wall of webbing to encircle surface schools of tuna. The net is set in approximately a circular area (subject to current and wave action) and then by drawing a purse line, the opening at the bottom of the net is reduced in area so that an escape route for the fish under of the net is eliminated. The net is then drawn aboard ship further reducing its size and concentrating the fish into a continually decreasing volume. Various techniques are utilized to recover the net and transfer the fish from the net onto the vessel. One technique which is commonly used is disclosed in U.S. Pat. No. 3,091,880 describing the well known technique of utilizing a power block for purposes of net handling and fish transfer.
Another technique of net handling is the so-called "drum seining method" which has been the subject of use on smaller coastal vessels for salmon fishing. Techniques of drum seining are summarized in detail in "Marine Fisheries Review", Vol. 36 No. 12, Dec. 1974, paper 1105, "Puget Sound Drum Seining", by William L. High. Drum seining techniques do not require the use of power blocks to lift the net over and onto the deck. They generally rely on a drum which is disposed on the stern of the vessel which may be rotated for operation either at the vessel side or transom. Also, although not directed to drum seining per se, the technique of net setting and retrieval in such systems utilizing pivoting drums is disclosed in U.S. Pat. No. 3,938,274.
In such systems the net is initially unwound from the drum at a controlled rate while the ship circumscribes a wide circle approximately the same circumference as the length of the net. A power skiff is deployed from the vessel and is used to hold one end of the net by means of a tow line during this laying operation. Positive floation keeps one edge of the net at or near the surface while ballast carries the lower edge to a desired depth. The circle is complete when the tow line initially carried by the skiff is brought back to the fishing vessel. A pursing line which extends as a cord across a portion of the bottom edge of the net is then drawn so that the net is "pursed" or drawn upward along its bottom edge to prevent the fish from escaping by diving below the net. As the pursing operation continues the overall circumference of the net is decreased the trap the fish. The drum is them again actuated to pull the net toward the vessel with the skiff disposed opposite the vessel to hold the net away from the vessel. That is, since the drum is drawing the net toward the vessel, in these prior art systems, the vessel will at the same time be drawn inexorably toward the net by operation of the drum. To prevent the net from fouling, the skiff is positioned, on station at an opposite point on the circumference of the net and holds it away from the vessel.
As the circumference of the net is reduced, near the vessel various techniques are utilized in the prior art to separate (brail) the fish from the net. U.S. Pat. No. 3,938,274 shows one unconventional technique utilizing a suction device placed amidships so that the fish are drawn into the vessel. More conventional techniques utilize baffles of the like to strip the fish from the net as it is drawn onto the vessel.
Once onboard the ship the fish may be frozen, and stored in holes until the fishing operations are complete and the vessel returns to port.
The ability of such vessels to operate efficiently and in unfavorable environmental conditions off-shore is a continuing requirement for increasing the capability of such fishing operations. Commercial fishing is very cost sensitive and time spent off-shore until the holds are full should be minimized. Efficient techniques to permit completion of the fishing task in a reduced time frame lower costs, allows the vessel to make more trips and improve profits. The use of drum seiners represents a considerable improvement over traditional power block systems in terms of the time to make a set of the net. However it has been generally used only on small coastal craft. Reduction in net setting time is deemed to be an important criteria since the greater number of sets that can be made on a run of fish, the greater the production and hence increased profitability. For example, traditional power block operations on conventional tuna vessels have the capability of making approximately 4 or 5 net sets in one 24 hour work day. Drum seiners allow about 10 sets in the same time period and offer increased flexibility since pursuing may occur with any amount of the drum set whereas, in power block systems the entire net must be discharged in order to purse the set. However, to date drum seiners have not been used in off-shore operations.
Additionally, in prior art systems whether they be power block operations or drum seiners, utilize a skiff to position and hold the net. The use of the skiff introduces an element of risk since this small boat cannot be safely discharged or retrieved from the fishing vessel in rough weather. Also, the working positions of personnel aboard the skiff are unsafe since they are continuously reaching over the side of the boat to retrieve and hold portions of the net. In rough or choppy water this operation is inherently dangerous. Another safety factor which has given rise to accidents in prior art systems particularly power block operations is that net retrieval and separation of fish from the net is done by positioning the net overhead the working deck by means of booms and the like, for example as shown in U.S. Pat. No. 3,091,880. As a result, material dropping out of the net, falling fish, sticks, or the like can strike and injure crew. Additionally, severe stings from jellyfish chemicals which tend to drop out of the net into the eyes and face of crewmen looking upward is an occupational hazzard. Moreover, broken purse rings and the like may fall as the net is retrieved during power block operations. Accordingly, prior art systems utilizing power blocks located on overhead booms have presented severe problems with respect to occupational hazzards.
Commercial tuna fishing utilizing prior art systems is as briefly mentioned, a labor intensive operation in addition to having severe operational constraints thereby inhibiting efficiency. Power block operations require crew to man the skiff, separate fish from the net, and manually haul portions of the net onto the vessel. While drum seining systems have reduced manpower requirements compared with power block operation, such prior art systems are still labor intensive in terms of crew requirements for skiff operations and brailing by hand.
Another operational aspect of off-shore fishing that is labor intensive is the handling of fish once onboard. Traditional systems require manual fish transport from the receiving area on deck and placement of fish in appropriate holds for storage. In the context of systems operating at approximately 50-75 tons of fish per hour the labor requirements are severe.